The continued, courtroom-wide presence of wigs that look 500 years old provides more than enough evidence of a judicial system’s resistance to modern updates.

Still, the underwritten thriller “Closed Circuit” spends considerable time summarizing the United Kingdom’s questionable practice of confining certain information to closed court, to the point that the defense attorney and defendant wouldn’t hear the sensitive material. It’s up to a special advocate to persuade a judge that the evidence should be shared with everyone—national security concerns (or otherwise) notwithstanding.

Martin (Eric Bana) takes over defending a suspect in the bombing of a London market after the Turkish-born man’s previous lawyer seems to have committed suicide. Claudia (Rebecca Hall) is the special advocate on the case. Martin and Claudia have a romantic past because that’s always the deal in movies like this. Can anyone uncover the truth behind an attack that killed 120 people without legal procedure or a variety of dirty secrets getting in the way?

The special advocate and defense lawyer can’t legally communicate, but there wouldn’t be much of a movie otherwise. When characters aren’t constantly reiterating the importance of this case, Steven Knight’s (“Dirty Pretty Things”) script has some snappy dialogue. Jim Broadbent, Ciaran Hinds and Riz Ahmed help the movie’s fringes come to life, though Julia Stiles has virtually nothing to do as a journalist who doesn’t really do anything. This is a familiar surveillance story that hasn’t been fleshed out enough to offer twists, only soft inevitabilities and a resolution that makes a point that’s been hammered home many times before—and then chickens out on its impact.

Modest and OK for a lazy Sunday afternoon on the couch, “Closed Circuit” is recommended for people who like their political thrillers easily unraveled and even more easily forgotten.

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